Synthesis, characterization and applicability of three isotope labeled azobenzene photoswitches.

We describe a short, efficient approach for the synthesis of three novel isotope labeled azobenzene photoswitches. The synthesis is based on commercially available fully isotope labeled precursors. The target molecules have been obtained in good yields, checked for purity, and identified by NMR and IR spectroscopy and a variety of standard analytical methods (UV-vis, mp, ESI-MS, elemental analysis). Using conventional coupling techniques the three isotope labeled photoswitches can be incorporated very easily in biomacromolecules.